Such apparatus generally utilize a medicament cartridge in which a medicament is stored and comprise a microprocessor that controls a drive mechanism to deliver a controlled dosage of medicament through a needle arrangement. The apparatus are small enough readily to be carried about by a user. As such, the apparatus is particularly suitable for use by those with diabetes.
The disclosure is also suitable for other kinds of medicament injection apparatus, for example injection apparatus in which though the dose setting and dose delivery are purely mechanical in character a timer is actuated following completion of a dose delivery stroke to indicate a time elapsed since completion of dose delivery stroke.
In each case, in use, once a desired dosage of medicament has been selected a needle unit of the medicament injection apparatus is inserted into a body of a patient. The drive mechanism is then actuated to cause the selected dosage of medicament to be expelled from the medicament cartridge into the body of the patient.
However, it is necessary once the injection has been made to allow the injected medicament to disperse locally from the injection site within the patient's body before removing the needle arrangement from the patient's body.
It is considered to be a problem that in known medicament injection devices the injection interval, that is the time elapsed since a previous injection, is measured following completion of a delivery stroke rather than from dispersion of the injected medicament.